The present invention relates to a retainer subassembly for use with the master link of an endless chain and particularly relates to a retainer subassembly for readily and easily engaging the free ends of the pins of a master link for a chain.
Endless chains typically have a master link which forms the final link in the chain during assembly and disassembly of the chain. The master link typically includes a pair of pins having annular grooves adjacent free ends and connected to one another at their opposite ends by a link. The pins pass through roller links thereby joining the opposite ends of the chain to one another through the master link to form an endless chain. The free ends of the pins of the master link, once inserted through the roller pins of the adjoining chain ends, are conventionally connected to one another by a retainer plate overlaid by a spring clip. The spring clip is typically a generally U-shaped clip having a pair of openings, the margins of which engage in the annular grooves of the free ends of the pins. The U shaped clip is resilient and thus the legs of the clip can be separated one from the other to engage the pin ends in the respective openings of the spring clip. When the clip resiliently closes, the clip retains the retainer plate and roller links on the roller pins of the chain and hence retains the chain in its endless chain configuration.
There are number of problems associated with a spring clip of this type for use with a chain master link. For example, the legs of the spring clip may come separated from one another enabling the spring clip to disengage from the annular groove or grooves of the pin ends. Should that occur, the retainer plate may be freed from one or both of the pin ends with the result that the roller links can become separated from the pins separating the chain. Additionally, the spring clip is somewhat difficult to apply to the master link and also to remove from the master link. The spring clip is relatively small in size and difficult to handle rendering it difficult to open the legs of the clip against their bias to apply the clip to the pin ends. Moreover, in both applying the spring clip to the master link pins and removing it from those pins, the bias at the clip legs sometimes causes the clip to spring off the master link and poses a danger to the individual attempting to assemble or disassemble the chain. Further, the spring clip must be in a position such that its open end faces reverse to the direction of chain rotation and if not faced in that direction, the spring clip is prone to snagging and may possibly be torn loose from the chain during operation. Accordingly, there is a need for a retainer subassembly for use with a conventional master link which is easy to apply and remove from the master link, does not require a tool for securing the retainer subassembly to the master link and which retainer subassembly may be simply be snapped into place.
In a preferred embodiment of the present invention, there is provided a retainer subassembly for application to the free or distal ends of the pins of a master link which is easy to apply and remove relative to the chain, does not require any tool for applying the retainer subassembly to the master link, does not require orientation relative to the master link, and is simply snapped onto the master link with the assurance that the retainer subassembly has been properly installed. Particularly, the retainer subassembly in a preferred form hereof includes a strap plate, a pair of snap rings and a cover plate. The strap plate has a pair of openings spaced from one another corresponding to the spacing of the pins of the master link for receiving the free ends of the master link pins. The cover plate includes a pair of recesses or counterbores along one side of the plate for receiving the snap rings. The recesses are spaced along the plate from one another in distance corresponding to the spacing between the pins of the master link and hence in assembly register with the openings of the strap plate. The snap rings are applied in the recesses of the cover plate. The snap rings comprise an annular outer band having circumferentially spaced radially inwardly directed flanges or tangs inclined axially outwardly of the plane of the annular outer band. The tangs or flanges project into the smaller diameter stepped recess of the cover plate and face outwardly away from the master link in final assembly.
To employ the retainer subassembly hereof, the cover plate, snap rings and strap plate are preassembled and secured to one another by a fastener for example a rivet passing through the cover plate and the strap plate. The flanges or tangs of the snap rings have an inner diameter less than the diameter of the pins. By applying the assembled retainer to the ends of the pins with the strap plate engaging over the pin ends, it will be appreciated that the tangs or flanges flex resiliently outwardly into the smaller diameter recesses as the pins are received through the snap rings and into the cover plate openings. Once past the outer ends of the pins, the flanges or tangs resiliently return to engage in the grooves of the pin ends to retain the retainer subassembly on the master link. Thus it will be appreciated that the retainer may be simply pushed onto the ends of the pins of the master link and is retained on the master link by the engagement of the tangs or flanges in the grooves of the free ends of the pins.
In a further form of the present invention, the retainer subassembly may comprise a retainer plate having spaced openings corresponding to the spacing of the pins of the master link. The openings of the retainer plate are larger in diameter than the diameter of the pins of the master link. In a recessed outer face of the retainer plate extending between the openings, a flat leaf spring is secured in a longitudinally extending groove such that its opposite ends terminate within the openings of the retainer plate. The retainer plate may then be applied over the free ends of the pins of the master link. As the retainer plate is applied, the spring ends flex outwardly and then snap into engagement in the annular grooves of the pins to retain the retainer plate on the master link. Preferably the outer ends of the pins of the master link beyond the annular grooves may be bevelled to facilitate passage of the outer pin ends past the spring ends upon application of the retainer plate to the master link.
In a still further form of the present invention, a single retainer plate having spaced openings corresponding to the spacing of the master link pins is provided. Each opening has a step along its interface. Each pin has a reverse bent leaf spring with one leg secured to the end of the pin. When the retainer plate is applied to the pin ends mounting the bent leaf springs, the margin of each opening flexes the free end of the leaf spring inwardly. Once past the end of the leaf spring, it flexes resiliently outwardly to engage in the step preventing removal of the retainer plate from the master link. The retainer plate is prevented from inward movement by shoulders on the pins of the master link or by the roller links connecting the master link to the reminder of the chain.